Combustion analysis of toluene, a common organic solvent, gives 7.03 mg of CO2 and 1.64 mg of H2O. If the compound contains only carbon and hydrogen, what is its empirical formula

The empirical formula for the given compound is CH

Explanation:

The chemical equation for the combustion of hydrocarbon having carbon and hydrogen follows:

where, 'x' and 'y' are the subscripts of Carbon, hydrogen and oxygen respectively.

We are given:

Mass of

Mass of

We know that:

Molar mass of carbon dioxide = 44 g/mol

Molar mass of water = 18 g/mol

For calculating the mass of carbon:

In 44 g of carbon dioxide, 12 g of carbon is contained.

So, in 0.00703 g of carbon dioxide, of carbon will be contained.

For calculating the mass of hydrogen:

In 18 g of water, 2 g of hydrogen is contained.

So, in 0.00164 g of water, of hydrogen will be contained.

To formulate the empirical formula, we need to follow some steps:

Moles of Carbon =

Moles of Hydrogen =

For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 0.00016 moles.

For Carbon =

For Hydrogen =

The ratio of C : H = 1 : 1

Hence, the empirical formula for the given compound is